Accuracy of preimplantation diagnosis of single-gene disorders by polar body analysis of oocytes

Purpose: A number of pitfalls in single-cell DNA analysis, including undete cted DNA contamination, undetected allele drop out, and preferential amplif ication, may lead to misdiagnosis in preimplantation genetic diagnosis of s ingle-gene disorders. Methods: Preimplantation generic diagnosis was performed by sequential firs t and second polar body analysis of oocytes in 26 couples at risk for havin g children with various single-gene disorders. Mutant genes were amplified simultaneously with linked polymorphic markers, and only embryos resulting from the mutation-free oocytes predicted by polar body analysis with confir mation by polymorphic marker testing were transferred back to patients. Results: Overall 529 oocytes from 48 clinical cycles (26 patients) were tes ted, resulting in the transfer of 106 embryos in 44 clinical cycles. As man y as 46 (9.6%) instances of allele dropout were observed, the majority (96% ) of which were detected. Seventeen unaffected pregnancies were established , of which nine resulted in the birth of an unaffected child, and the rest are ongoing. Conclusions: A high accuracy of preimplantation genetic diagnosis of single -gene disorders is achieved by application of sequential analysis of the fi rst and second polar body and multiplex polymerase chain reaction.